[3.5.y.z extended stable] Patch "net: clamp ->msg_namelen instead of returning an error" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    net: clamp ->msg_namelen instead of returning an error

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From c99dc96702fea64019a73906fd4ddd8381e10dd8 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter at oracle.com>
Date: Wed, 27 Nov 2013 15:40:21 +0300
Subject: net: clamp ->msg_namelen instead of returning an error

commit db31c55a6fb245fdbb752a2ca4aefec89afabb06 upstream.

If kmsg->msg_namelen > sizeof(struct sockaddr_storage) then in the
original code that would lead to memory corruption in the kernel if you
had audit configured.  If you didn't have audit configured it was
harmless.

There are some programs such as beta versions of Ruby which use too
large of a buffer and returning an error code breaks them.  We should
clamp the ->msg_namelen value instead.

Fixes: 1661bf364ae9 ("net: heap overflow in __audit_sockaddr()")
Reported-by: Eric Wong <normalperson at yhbt.net>
Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
Tested-by: Eric Wong <normalperson at yhbt.net>
Acked-by: Eric Dumazet <edumazet at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/compat.c | 2 +-
 net/socket.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/compat.c b/net/compat.c
index b4afcb4..1d223d5 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -72,7 +72,7 @@ int get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr __user *umsg)
 	    __get_user(kmsg->msg_flags, &umsg->msg_flags))
 		return -EFAULT;
 	if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
-		return -EINVAL;
+		kmsg->msg_namelen = sizeof(struct sockaddr_storage);
 	kmsg->msg_name = compat_ptr(tmp1);
 	kmsg->msg_iov = compat_ptr(tmp2);
 	kmsg->msg_control = compat_ptr(tmp3);
diff --git a/net/socket.c b/net/socket.c
index 5febb56..b04050a 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1907,7 +1907,7 @@ static int copy_msghdr_from_user(struct msghdr *kmsg,
 	if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
 		return -EFAULT;
 	if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
-		return -EINVAL;
+		kmsg->msg_namelen = sizeof(struct sockaddr_storage);
 	return 0;
 }

--
1.8.3.2